Should a Van Nuys built 70 Chevelle M20 have a 10 spline or 26 spline input shaft? Car was built January of 1970. Where should I look for the vin #?

Pretty sure all the M20's are 10 spline input shaft. Mine is.

Should a Van Nuys built 70 Chevelle M20 have a 10 spline or 26 spline input shaft? Car was built January of 1970. Where should I look for the vin #?

I'm not sure when they made the switch to the heavy duty muncie but I know it was late in the production run.

The partial Vin is stamped in the case, near the place where the identification is stamped, on the passenger side. You have the "P----A" for M20 and the partial vin will be very near that.

Pretty sure all the M20's are 10 spline input shaft. Mine is.

All muncies made from late 70 to the end of production, 74, where fine spline imput and 32 spline output. They all had drain plugs as well.

When does "late 70" begin? I've heard the term for years, but I've never heard anyone define it as a specific date.

When does "late 70" begin? I've heard the term for years, but I've never heard anyone define it as a specific date.

I'm guessing, but May or later. If your car is a Jan. car, the trans could have been built in december. It's not uncommon to see 2 to 3 weeks difference in the trans date and the assembly date.

So there is no "official differentiation between "early" and "late" 70 for Chevelles? At least it's obvious between the early and late camaros. The trans is a coarse spline, but since I have it apart I want to make sure it's the correct parts before i put it back together.

So there is no "official differentiation between "early" and "late" 70 for Chevelles? At least it's obvious between the early and late camaros. The trans is a coarse spline, but since I have it apart I want to make sure it's the correct parts before i put it back together.

Does the trans have the right VIN number on it???

From 1971 thru the 1974 model year all Muncie 4-speeds were 26 spline input/ 32 spline output...
In 1970 only big block M-22 Chevelles got the 26 spline input/ 32 spline output...

Hope this helps... Crash

Does the trans have the right VIN number on it???

I've got to go check it. I took it apart last fall and I've gotten sidetracked. The guy i bought it from siad it was the original one, but it was really greasy and i never looked for it all that hard. I think 20 years is long enough and I probably ought to put it back together.

From 1971 thru the 1974 model year all Muncie 4-speeds were 26 spline input/ 32 spline output...
In 1970 only big block M-22 Chevelles got the 26 spline input/ 32 spline output...

Hope this helps... Crash

I've seen some sources say that the fine splines started in 70, others say 71. My Chevrolet Parts Catalog (rev 6-1-70) does not list the numbers of splines for the input shafts for the M20 or the M21. The catalog lists both a 10 spline (3925691) and a 26 spline (3978761) for the M22. The M20 and M21 both only list 1 input shaft. And this is a 1970 ONLY catalog. No other years are listed. If anyone knows if there are part numbers listed on the gears and where to find them, I guess this will answer the question.

I've seen some sources say that the fine splines started in 70, others say 71. My Chevrolet Parts Catalog (rev 6-1-70) does not list the numbers of splines for the input shafts for the M20 or the M21. The catalog lists both a 10 spline (3925691) and a 26 spline (3978761) for the M22. The M20 and M21 both only list 1 input shaft. And this is a 1970 ONLY catalog. No other years are listed. If anyone knows if there are part numbers listed on the gears and where to find them, I guess this will answer the question.

Having GM part numbers for the gears is not much help, you can't get them new, once in a while they turn up as NOS on FleBay, be very wary of these.

I have a GM parts book, I'll look through it later and see if I can find the numbers.

Having GM part numbers for the gears is not much help, you can't get them new, once in a while they turn up as NOS on FleBay, be very wary of these.

I have a GM parts book, I'll look through it later and see if I can find the numbers.

I have the numbers listed above. Ae they stamped on the gears anywhere?

From 1971 thru the 1974 model year all Muncie 4-speeds were 26 spline input/ 32 spline output...
In 1970 only big block M-22 Chevelles got the 26 spline input/ 32 spline output...

Hope this helps... Crash


Crash,
This is in reference ONLY to 1970 GM cars.

Other than the 70BB Chevelles, did any other 70 GM cars (such as Vette, GTO, etc) WHICH GOT A FACTORY INSTALLED M22, have the 26spline input/32spline tail shaft?
This seems to be somewhat debateable that the 26spline input/32spline tail shaft (M22) was unique ONLY to the 70BB Chevelle. Some 70 454/M22 Vette owners claim their 70 Vette had the 26/32 spline versions.